<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <div v-show="isActive">{{message}}</div>
        <!-- <div v-else-if>{{message}} -- else</div> -->
        <!-- {{message}} -->
    </div>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.12/vue.min.js"></script>
    <script>
        var app=new Vue({
            el: '#app'
            , data: {
                message: 'msg'
                ,isActive:false
            }
            ,updated(){
                debugger
            }
          
        })
    </script>

</body>

</html>